Issue Archive

MMIC multi-chip modules can be used in astrophysics telescopes, automotive radar, and
communication links.

A single-pixel prototype of a W-band
detector module with a digital backend
was developed to serve as a building
block for large focal-plane arrays
of monolithic millimeter-wave integrated
circuit (MMIC) detectors. The
module uses low-noise amplifiers,
diode-based mixers, and a WR10 waveguide
input with a coaxial local oscillator.
State-of-the-art InP HEMT (high
electron mobility transistor) MMIC
amplifiers at the front end provide
approximately 40 dB of gain. The
measured noise temperature of the
module, at an ambient temperature of
300 K, was found to be as low as 450 K
at 95 GHz. The modules will be used to develop
multiple instruments for astrophysics
radio telescopes, both on the ground
and in space. The prototype is being
used by Stanford University to characterize
noise performance at cryogenic
temperatures. The goal is to achieve a
30–50 K noise temperature around 90
GHz when cooled to a 20 K ambient
temperature. Further developments
include characterization of the IF inphase
(I) and quadrature (Q) signals
as a function of frequency to check
amplitude and phase; replacing the
InP low-noise amplifiers with state-ofthe-
art 35-nm-gate-length NGC low-noise amplifiers; interfacing the frontend
module with a digital back-end
spectrometer; and developing a
scheme for local oscillator and IF distribution
in a future array.

While this MMIC is being developed
for use in radio astronomy, it has the
potential for use in other industries.
Applications include automotive radar
(both transmitters and receivers), communication
links, radar systems for collision
avoidance, production monitors,
ground-penetrating sensors, and wireless
personal networks.

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